This invention relates in general to a kind of multipurpose writing device, and more particularly to a combination writing instrument which comprises a pen holding means with a mother pen nib, over which a pularlity of detachable sub-pen nibs are successively mounted one by one.
In conventional writing instruments, as each individual writing point requires its distinctive ink flow system so that when they are designed to mount in a manner of head-to-tail configuration, ink often does not feed smoothly from the ink reservoir to the point of the front-most writing nib. Moreover, if such configuration of writing instrument is positioned upsidedown for a period of time, ink retained in the front-most writing point will be sucked rearward the next successive pen nib or ink reservoir, especially when fountain pen nib is put in the front-most position. In this way, smooth writing at the beginning is not possible, and sometimes the pen will become unusable. For example, in a writing device such as described in U.S. Pat. No. 3,572,954, the rate of ink flow in marking member 17 is greater than that of sponge tongue 42, as shown in FIG. 3, when the whole writing device is positioned in an upsidedown position, i.e. put it in a shirt pocket, according to the present inventor's experimentation it is found that all ink retained in nib device B will soon be sucked back by the marker A so that at the beginning of each usage, no ink flow is attained immediately. Another problem is that when the front point 19 of stem 17 is worn away after a period time or when sponge 44 becomes aged, the length of the front-most writing tip 19 becomes shorter, the ink flow system will thus become unworkable.
In order to improve this drawback, Cheron further provides a washer 53 and orifice 54 as shown in FIGS. 4 and 5 to extend the contact area of tongue 42 and tip 19. However, the above mentioned drawbacks still can not be overcome, as the periphery of the sponge washer 53 provides no limitation means, so that when tip 19 is inserted therein, due to its swelling freely from the center to the outside, there is no benefit in attaining contact, especially while the front-most writing point is being worn away, a gap will be formed between washer 53 and tip 19 as shown in FIG. 9 of the attached drawings.
In order to make a further improvement, Cheron also provides a folded branch 128 at the end of stem 125 as shown is FIG. 10 of the attached drawing of the invention (corresponding to FIG. 12 of Cheron's patent). However, the diameter d2 of contacting area A2 between rear folded end of stem 125 and tracing point 63 is only one half of the diameter d1 of cross-sectional area A1 of stem 125, so that the total amount of ink flow from the tracing point 63 to the stem 125 will be only one quarter of that needed by the stem 125 to the ball 122. Therefore, when ball 122 is made to rotate rapidly for fast writing, ink supply to the ball 122 will soon be insufficient, causing broken lines and generally unsmooth writing.
In addition, with the excepting of the front portion of stem 125, the periphery of remaining length portion of stem 125 is free control. According to experiment by the present inventor, it has been found that at the time of the wet state of sponge, due to its swelling, the rear folded portion 128 of stem 125 will move toward the front as shown by arrow R1 and away from center as shown by arrow R2. This result may make the contacting area A2 become increasingly smaller. Moreover, the majority of the outer surface of stem 125 is exposed to the air, so ink contained inside the stem 125 may be easily evaporated, and ink residue may remain therein and disrupt the ink feeding function to the stem 125.
As described by Cheron, all the stems used in his patent are made from a synthetic sponge having a high coefficient of swelling. This means that excellent swelling function of a material like synthetic sponge retains a great deal of ink within the stem. In other words, it provides an excellent retention of ink inside the stem, but inferior conveyance of ink from one end of the other end. This means that basically, synthetic sponge material can not be used for the ink feeding material.
After extensive research, testing and improving, the present inventor has developed a combination writing instrument which provides multi-writing purposes with applicable writing modes.
The primary objective of the present invention is to overcome the defects of conventional fountain pens, ball point pens and sign pens which when combined together are not able to provide consistent smooth writing, and offer a combination writing instrument wherein a main nib device fits on the pen holding means and a plurality of sub nib devices are connected in a head-to-tail configuration to provide a constant ink flow system and attain smooth writing.
Another objective of the present invention is to provide a combination writing instrument having a single nib device with a series of different gauges for different kinds of drawing lines required, such as solid lines, shading lines, etc.
A further objective of the present invention is to provide a multi-purpose writing instrument of simple construction having easily exchangeable nib device devices and providing a uniform ink flow system to perform the most smooth writing any time and anyplace.
A still further objective of the present invention is to provide a multi-purpose writing instrument with a series of soft ink conducting means immediately provided at the rear end of each nib device and closely contacting the individual ink inducing means of each nib device to further ensure close contact of the largest possible area between each two nib devices to thereby form a part of uniform ink flow system and to assure smooth writing.
The above and other objects, features and advantages of the present invention will become more apparent when taken in conjunction with the apended drawings.